This invention relates to fluoropolymeric orthodontic articles.
Orthodontic treatment often involves the application of mechanical forces to urge improperly positioned teeth into correct alignment. One common form of orthodontic treatment includes the use of orthodontic brackets affixed to the surface of a tooth, and a resilient curved arch wire seated in slots on the brackets. The arch wire exerts a restoring force on the teeth which tends to shift the teeth into orthodontically correct alignment.
Orthodontic articles such as, e.g., brackets, were traditionally formed from metal, but more recently have been formed from plastic and ceramic. Plastic brackets can be fabricated to be translucent to transparent in character relative to metal brackets. It is often difficult, however, to maintain the aesthetic characteristics of plastic brackets during use because food and beverages can stain and discolor the brackets while they reside in a patient""s mouth.
In one aspect, the invention features an orthodontic article (e.g., an orthodontic bracket) that includes a fluoropolymer and that exhibits at least about 0.001% transmittance at 546 nm when measured according to the Transmittance Test Procedure described herein. In another embodiment, the article exhibits at least about 0.01% transmittance at 546 nm when measured according to the Transmittance Test Procedure. In other embodiments, the article exhibits a transmittance of at least about 0.001% over a wavelength range of from 400 nm to 800 nm when measured according to the Transmittance Test Procedure.
In one embodiment, the article exhibits a Delta E color shift of no greater than about 2 when tested according to the Hydrophilic Color Shift Test, and a Delta E color shift of no greater than about 5 when tested according to the Oleophilic Color Shift Test.
Suitable fluoropolymers are selected from the group consisting of perfluoroethylene-propylene copolymer, perfluoroalkoxyethylene, ethylene-tetrafluoroethylene copolymer, polyvinylidenefluoride, polyvinylfluoride, polychlorotrifluoroethylene, ethylene-chlorotrifluoroethylene copolymer, and combinations thereof. In one embodiment, the fluoropolymer includes perfluoroethylene-propylene copolymer. In another embodiment, the fluoropolymer includes perfluoroalkoxyethylene. In other embodiments, the fluoropolymer includes ethylene-chlorotrifluoroethylene copolymer.
The article may further include a polymeric composition disposed on a surface of the article, where the polymeric composition includes an organoborane compound. In another embodiment, the article further includes an organoborane amine complex disposed on a surface of the article.
In another aspect, the invention features a method for using an orthodontic bracket, where the method includes: (a) contacting a fluoropolymeric orthodontic bracket having an average transmittance of at least 0.001% when measured according to the Transmittance Test Method with a composition that includes an organoborane compound; and (b) adhering the bracket to a tooth. In one embodiment, the method further includes: contacting the surface that includes an organoborane compound with a polymerizable component; and polymerizing the polymerizable component to form an adhesive composition. In other embodiments, the method further includes contacting a polyimide film with the composition that includes the organoborane compound prior to adhering the bracket to a tooth.
In another embodiment, the method further includes treating the organoborane treated surface with a polymerizable component, and polymerizing the polymerizable component. In one embodiment, the method further includes contacting the polymerized component treated surface with an adhesive composition.
In another aspect the invention features an orthodontic article that includes a fluoropolymer selected from the group consisting of perfluoroethylene-propylene copolymer, perfluoroalkoxyethylene, ethylene-tetrafluoroethylene copolymer, polyvinylidenefluoride, polyvinylfluoride, polychlorotrifluoroethylene, ethylene-chlorotrifluoroethylene copolymer, and combinations thereof. In one embodiment, the orthodontic article includes a bracket. The orthodontic article may further include a metallic component.
In another aspect, the invention features a kit for adhering an orthodontic article to a tooth. The kit includes an orthodontic article that includes a fluoropolymer having at least about 0.001% transmittance at 546 nm when measured according to the Transmittance Test Procedure; and an adhesive system that includes a) a polymerizable component; and b) an organoborane amine complex. In one embodiment, the organoborane amine complex is disposed on a surface of the orthodontic article. In another embodiment, the kit further includes a polyimide film.
The orthodontic articles are resistant to staining by food and beverages such as mustard and spaghetti sauce such that the article remains aesthetically pleasing in appearance and does not unduly darken or turn yellow during the time the article remains in the oral cavity. The orthodontic articles also maintain their essentially translucent to transparent character over the useful life of the article such that they transmit the color of the underlying tooth surface to which they are adhered.
Other features and advantages of the invention will be apparent from the following description of the preferred embodiments thereof, and from the claims.